Electronic tube



Feb. 9, 1943. w, w, EITEL 'ETAL 2,310,769

' ELECTRONIC TUBE Filed July l3 1942 2 Sheets-Sheet l INVENTORS WILL/AMIV. El

(1146' A M CU O ZIGH M? ""fHEIR ATTORNEY U w.- w. E'ITEL ET AL IELECTRONIC TUBE Feb. 9, 1943.

2 Sheets-Sheet 2 Filed July 13, 1942' W. EITEL ZLOUGH MA H WL A nPatented Feb. 9, 1943 ELECTRONIC TUBE William W. Eitel, San Bruno, andJack A.

McCullough, Millbrae, Califi, assignors to Eitel- McCullough, Inc., SanBruno, Calif., a corporation of California Application July 13,194.2,sena1-N0. 450,753

Claims.

Our invention relates to an electronic tube particularly adapted fortransmission purposes.

It is among the objects of our invention to provide an improvedstructure of, arrangement for and mounting of the electrodes and leadsin the envelope.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of our invention. It is to be understood that we do notlimit ourselves to this disclosure of species of our invention, as wemay adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings:

Figure 1 is a perspective view of a tube embodying the improvements ofour invention; and

Figure 2 is a vertical sectional view of the same.

In terms of broad inclusion, our tube comprises an envelope having are-entrant stem at one end. A plurality of coaxial electrodes includinga plate and grid and cathode are arranged in the envelope, the platebeing provided with a cap at one end thereof. The plate is supported bya bracket on the cap secured to a lead disposed coaxially with theelectrodes and sealed to the envelope end opposite the stem. The grid issupported on a lead sealed to a side of the envelope; and leads for thecathode are sealed to the stem.

In greater detail, and referring to the drawings,

our tube comprises an envelope of glass or the like having a globe-likebody I terminating at the top in a reduced neck 2 and at the bottom in alarger neck 3 carrying a re-entrant stem 4 having an exhaust tubulation5. The envelope is fitted with a cup-shaped base 6, say of porcelain,secured to neck 3 by a suitable cement 1. Prongs 8 of the usual typeproject from the base.

Within the envelope are arranged a plurality of electrodes including acathode 9, grid H and plate or anode l2. The plate is cylindrical inshape, and may be of any suitable metal, such as tantalum. It preferablycomprises a plurality of arcuate sections with flanges welded togetherto form heat radiating fins l3. Annular beads l4 in the sections holdtheir shape when formed in a die. After welding, the fins arecorrugated.

A hemispherical cap l5 of tantalum is secured over the upper end of thetubular plate by depending tabs |6 welded to the rim. Arched recesses l1formed in the cap between tabs [5 provide vent openings. This capprotects the glass dome against electron bombardment, and also adds tothe heat radiating surface of the plate structure.

Plate lead I8, preferably, of tungsten, is arranged coaxially with theelectrodes and projects through neck 2 at seal 19. A terminal button 2!]is secured on the external end of this lead. The plate is supported by abracket 2| welded at the lower end to cap l5 and at the upper end tolead 18. This bracket preferably comprises a pair of tantalum strapsshaped with curved feet at the bottom to fit the cap for convenience inwelding. The upstanding ends of the straps are grooved to embrace thelead, with laterally projecting portions providing heat radiating fins22 extending along the lead.

One of the problems in tubes is to prevent heat from flowing out to theglass and cracking the seal. Our structure overcomes this difliculty byreason of the mounting structure above described. As already mentioned,end cap l5 stops electron bombardment of the glass, and helps todissipate heat by radiation before it reaches lead l8. Fins 22 on thebracket also function to dissipate heat tending to flow out along thelead. Angularly disposed slits 23 in fins 22 serve to retard outwardflow of heat by conduction. These features, together with the fact thattantalum is not a good heat conductor, cooperate to thermally isolatethe plate lead and its seal from the heat zone at the electrodes.

Another feature of the plate mounting structure is that a nickel sleeve25 is interposed between tungsten lead It and the tantalum bracket.Nickel alloys or fluxes readily with both tungsten and tantalum,insuring a good welded joint between the parts. Furthermore, the weld isclean and free of oxides and contamination which, if present, makeoutgassing difficult during evacuation.

Grid H is of the cage type, preferably of platinum Wire, terminating ina tantalum base ring 25. This electrode is supported by a bracket 21 ona tungsten lead having an up-bent portion 28 and a transverse portion 29extending through the envelope side wall at seal 3!. This lead seal ispreferably formed in the cylindrical wall of neck 3. Bracket 21comprises a tantalum strap bent to embrace the upper end of lead portion28 and having end tabs formed to fit grid ring all parts being securedby welding. A nickel sleeve 32 is interposed between the bracket andlead to flux the weld at this point.

Filamentary cathode 9 comprises a coil of thoriated tungsten welded attop and bottom to a pair of tungsten leads 33 sealed to stem 4. Flexibleextensions 34 connect the lower ends of leads 33 with a pair of the baseprongs 8.

We claim:

1. An electronic tube comprising an envelope, a plurality of electrodesincluding a plate and grid in the envelope, a lead sealed to an end ofthe envelope, a cap on one end of the plate, means on the cap supportingthe plate on said lead, a lead sealed to a side of the envelope, andmeans supporting the grid on the last mentioned lead.

2. An electronic tube comprising an envelope, a plurality of coaxialelectrodes including a plate and grid in the envelope, a lead coaxialwith the electrodes and sealed to an end of the envelope,-

a cap on one end of the plate; means on the cap supporting the plate onsaid lead, a lead sealed to a side of the envelope, and means supportingthe grid on the last mentioned lead.

3. An electronic tube comprising anenvelope having a reentrant stem atone end thereof, a plurality of electrodes including a plate and gridand cathode in the envelope, a lead sealed, to the other end of theenvelope, a cap on one end of the plate, means on the cap supporting theplate on said lead,.a lead sealed to a side of the envelope, meanssupporting the grid on the last mentioned lead, and leads for thecathode sealed to said stem.

4. An electronic tube comprising an envelope having a reduced neck atone end thereof carrying a re-entrant stem, a plurality of electrodesincluding a plate and grid and cathode in the envelope, a lead sealed tothe other end of the envelope, a cap on one end of the plate, means onthe cap supporting the plate on the lead, a lead sealed to a side ofsaid neck, means supporting the grid on the last mentioned lead, and

